1. Field of the Invention
The present invention relates to a technique for allocating respective relative addresses of data storage media in a digital data player, and more particularly to an apparatus and method for allocating relative addresses for a plurality of multimedia cards in a digital data player with a multimedia card stack configured to receive those multimedia cards.
2. Description of the Related Art
One type of digital data player is an MP3 player which is a portable digital appliance capable of easily downloading desired data via a computer communication network and reproducing the downloaded data, using an audio data compression coding technique without using a tape or compact disc (CD). In particular, such an MP3 player exhibits little or no failures while having a good reproduction quality because it is configured to store reproduction files in the form of digital data. Also, the MP3 player has a light and miniature structure, so that it exhibits a superior portability and is capable of being carried during exercise. By virtue of such features, MP3 players are desirable substitutes for portable cassette players and CD players.
For such MP3 players, there are diverse types of storage media Separable multimedia cards (MMCs) are one type of such media mainly used as storage media for MP3 players.
FIG. 1 is a view illustrating the configuration of a general multimedia card. Referring to FIG. 1, the multimedia card 5 includes seven connection ports, that is, a clock port or terminal CLK, a data port or terminal DAT, a command/response port or terminal CMD, three power terminals VSS1, VSS2, and VDD, and a redundancy port NC. The terminals CMD, CLK, and DAT compose a 3-line serial data bus. Signals received at the terminals CMD, CLK and DAT are inputted to a card interface controller 13 via an interface driver 12 so as to control the inputting and outputting of data to and from a memory 15. Typically, the memory 15 of the multimedia card 5 comprises a ROM and a flash memory. A set of registers 16 are electrically connected to the card interface controller 13.
The command/response terminal CMD serves as a bi-directional command channel so that it is used for transmission of a card initialization signal and a data transmission command. A signal transmitted on the command/response terminal CMD, namely, a CMD signal, has two operation modes, that is, an open-drain mode for initialization, and a push-pull mode for a rapid command transmission. A command is sent from a multimedia card bus master to the multimedia cards whereas a response is sent from each multimedia card to a host The data terminal DAT is a bi-directional data channel. A signal transmitted on the data terminal DAT, namely, a DAT signal, operates in a push-pull mode. Such a DAT signal is driven by only one of an associated multimedia card or the host.
FIG. 2 is a block diagram schematically illustrating the configuration of a conventional multimedia card stack. Referring to FIG. 2, N multimedia cards 11A to 11N are illustrated, each of which includes a plurality of connection ports NC, CMD, VSS1, VDD, CLK, VSS2, and DAT, a memory adapted to store data therein and a card interface controller adapted to write data on the memory and to read out the stored data from the memory. The multimedia card stack is configured to allow the multimedia cards 11A to 11N to be connected to a multimedia card controller 10 included in an MP3 player, in which the multimedia card stack is located, while sharing a system bus. Not all slots in the stack need contain a card, and the cards need not be inserted into the slots in any particular order.
The multimedia card controller 10 is connected to a personal computer (PC) 40. When the PC 40 outputs a control command to the multimedia card controller 10, this multimedia card controller 10 reads out data from a selected one of the multimedia cards 11A to 11N in response to the control command, and outputs the read data to an MP3 decoder 20. The decoded data generated from the MP3 decoder 20 is then outputted in the form of an analog signal via a digital analog converter (DAC) 30.
A multimedia card system using multimedia cards 11 A to 11N mentioned above includes slots for inserting those multimedia cards (i.e., a multimedia stack provided with those slots) and a multimedia card controller for writing data on a memory included in a selected one of the multimedia cards, and reading out the stored data.
Now, a procedure for allocating different relative addresses to the multimedia cards of the multimedia card stack in accordance with an operation of the multimedia card controller will be described. Each of the multimedia cards 11A to 11N downloads data supplied from the multimedia card controller of the MP3 player or uploads data, already downloaded, via a reverse path. These cards share the ports associated with the downloading or uploading of data, and lines on a system bus, i.e., the clock line CLOCK, the command line COMMAND, and the data line DATA.
For such data downloading or uploading operations, all multimedia cards 11A to 11N in the multimedia card stack are allocated different relative card addresses (RCAs) by the multimedia controller in an initialization procedure, respectively. In this procedure, the relative address allocation is begun from the multimedia card of the cards 11A to 11N exhibiting a more rapid response to a command from the multimedia controller than the other cards.
In accordance with this relative address allocation method, it is impossible for the multimedia card controller to recognize respective relative addresses allocated for the multimedia cards inserted in particular slots of the multimedia card stack. In other words, although the multimedia card controller can recognize the number of multimedia cards inserted in the multimedia card stack, it cannot recognize respective positions within the stack and relative addresses of the cards inserted in the slots. For this reason, one drawback is that it is impossible to inform the user of respective positions of multimedia cards inserted in the multimedia card stack. In other words, the multimedia card to be accessed is determined in a random fashion irrespective of the intention of the user.
Accordingly, the present invention is directed to a technique for allocating respective relative addresses of data storage media in a digital data player that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In accordance with one aspect, the present invention provides relative address allocation apparatus for a digital data player having a plurality of slots respectively adapted to receive multimedia cards, including at least one multimedia card inserted in the slots and adapted to download or upload data, a plurality of switches each adapted to selectively supply a clock signal to an associated slot in response to an associated clock control signal; and a multimedia card controller to sequentially output clock control signals to the plurality of switches so as to sequentially select the slots, and to allocate a relative address for any multimedia card inserted in the selected slot.
In accordance with another aspect, the present invention provides a relative address allocation method for a digital data player having a plurality of slots adapted to receive multimedia cards, including outputting a clock control signal to one of the slots from a controller; tuning on a switch connected to the one slot, in accordance with the outputted clock control signal; and determining whether or not there is a multimedia card inserted in the one slot connected to the turned-on switch.
In accordance with another aspect, the present invention provides a relative address allocation method for a digital data player having a plurality of slots adapted to receive multimedia cards, said slots being connected to a common bus, the method including selecting one of the slots; connecting a terminal of the selected slot to the common bus; and assigning a relative address to any multimedia card present in the selected slot.
Therefore, it is an advantage of the present invention to allocate relative addresses to a plurality of multimedia cards in a digital data player one by one, so that respective positions of the multimedia cards inserted in the slots can be recognized thereby allowing respective RCAs to be allocated for the position-recognized multimedia cards.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.